1. Technical Field
The present invention relates to a recording tape cartridge which accommodates, within a case, a single reel on which is wound a recording tape such as a magnetic tape or the like used as a recording/playback medium mainly for computers or the like.
2. Description of the Related Art
Conventionally, recording tape cartridges (magnetic tape cartridges) have been known in which a magnetic tape, which is used as a data recording/playback medium for computers or the like, is wound on a single reel, and the reel is accommodated within a case formed of a synthetic resin. Such a recording tape cartridge is equipped with a braking means so that the reel does not rotate within the case when the recording tape cartridge is not being used (is not loaded in a drive device).
As the braking means, there are structures which, for example, cause a braking member, which cannot rotate with respect to the case, to engage with the reel, or the like. Namely, as shown in FIG. 7, a braking member 130 is formed in the shape of a disc which is accommodated so as to be movable upward and downward within a reel hub 112 of a reel 110. The reel hub 112 is formed in the shape of a hollow cylinder having a floor. A pair of engaging projections 134, which are substantially U-shaped as seen in plan view, stand erect from the top surface of the braking member 130. A pair of rotation restricting ribs 126, which are provided vertically from the inner surface of an upper case 122, are inserted in the engaging projections 134, such that the braking member 130 cannot rotate with respect to a case 120. Moreover, by an urging means such as a compression coil spring 116 or the like, the braking member 130 is always urged toward a floor wall 114 of the reel hub 112, and an annular braking gear 132, which is formed at the bottom surface of the braking member 130, is made to mesh together with an annular engaging gear 118 which is formed at the top surface of the floor wall 114 of the reel hub 112. Inadvertent rotation of the reel 110 is thereby impeded.
A substantially solid cylindrical operation projection 136 projects at the axially central portion of the bottom surface of the braking member 130. The operation projection 136 is inserted in a pass-through hole 114A formed in the axially central portion of the floor wall 114 of the reel hub 112, and faces a gear opening 128 formed in the substantially central portion of a lower case 124. Accordingly, when the reel 110 is to be made to be rotatable, the operation projection 136 (the braking member 130) is pushed upward, such that the meshing-together of the braking gear 132 with the engaging gear 118 is cancelled (see, for example, U.S. Pat. No. 6,452,747).
However, with such a structure in which the meshing-together of the braking gear 132 with the engaging gear 118 is cancelled by the operation projection 136 (the braking member 130) being pushed upward in this way, if a user carelessly pushes the operation projection 136 upward in fun or the like, as shown in the figure, there are cases in which the braking member 130, in a tilted state, anchors on the peripheral edge portion of the pass-through hole 114A (i.e., tilts). If the recording tape cartridge is loaded into a drive device in this state, not only will recording and playback not be possible, but also, breakage of the recording tape cartridge or malfunctioning of the drive device may be caused. Moreover, there is also the problem that it is easy for dust and the like to enter in from the pass-through hole 114A.